Mark gets Polar off to a quick start as the season opens, sending Alex and Todd onto the ice roads early. Alex notes cracks and holes in the ice as he crosses the Hayes River, hauling a camp shack to Shamattawa. The next morning, he brings the load in. While taking an emergency load of heating supplies to Wasagamack, Todd skids badly on the slick road and slides into a snowbank. By looping a strap around a tree and one axle, he improvises a winch and pulls himself free so he can continue his run and make the delivery by day's end.

Still in business for himself, Darrell quickly secures two emergency loads of building supplies needed in Garden Hill. He takes Lisa on as a partner, offering her partial ownership of the company, and the two set out. Shortly into the run, though, Lisa's truck loses power and she is forced to return to Winnipeg for repairs. She loses half a day waiting on it to be fixed, then hurries to make up for lost time. Darrell reaches Garden Hill the next morning, and Lisa comes in just in time to meet the deadline.

Mark sends Todd out with a load of heating supplies that must reach Wasagamack by the following morning. After spinning out on a hill that night, he spends several hours digging his wheels free so he can complete the delivery on time. Meanwhile, Alex delivers a load of groceries donated by Polar to a food drive in St. Theresa Point. At his destination, the village chief gives him a painting as a token of appreciation. Carrying lumber to Garden Hill, Art must negotiate a rough road that is frozen solid and dotted with flags that mark dangerous spots. The final obstacle is a 10-mile ice crossing whose weight limit is barely high enough to accommodate his truck, but he completes the run safely after nearly an hour on the ice.

Mark sends Todd to Pikangikum with a crane weighing 130,000 pounds, the heaviest load moved by Polar to date. Despite Mark's assurances that the road's ice crossing will be kept clear for Todd, he encounters an oncoming truck on the ice. It quickly turns around and retreats onto the shore, and he delivers the crane safely. Art hurries to St. Theresa Point to pick up a trailer abandoned from the previous year; it is needed in Winnipeg for a haul the next morning. After skidding his way through the final 50 miles of the trip, he finds the trailer stuck in deep frozen snow. He uses a loader parked in the yard to dig out the tires, but they are still frozen to the ground and he must shovel them off by hand. After working for a total of 14 hours, he pulls the trailer free that night and starts the return trip to Winnipeg.

Mark hires a new driver, Mike Simmons, and sends him out with Art for his first run. The two are hauling building supplies and pontoon boats to the fishing resort of Elk Island Lodge, 400 miles away. Both Mark and Art express concerns over Mike's cocky attitude and lack of ice road experience. Art's speed challenges Mike to keep pace on the rough roads; that evening, they come to a 10-mile ice crossing that is not maintained by public road crews. Night falls as they make their way across the ice, and Art tries to calm a jittery Mike with an impromptu poetry recital. Once they reach their destination, Art congratulates Mike for his first successful ice road run.

Todd takes building supplies to Muskrat Dam, whose ice road has just opened, and must fight through bumps and ruts that threaten to shake his load off the trailer. A hard jolt knocks the plug out of his compressed air tank, causing a leak that locks his brakes, and he finds himself stranded with no way to repair the leak or call for help. As Alex heads to Big Trout Lake with a load of building supplies, he encounters several unmarked forks and intersections in the road. Choosing the paths with the most signs of use, he successfully delivers his cargo the following morning.

With temperatures rising several weeks earlier than in past years, roads and ice crossings are rapidly deteriorating. Darrell and Lisa secure their biggest contract to date: two electrical transformers that must reach Deer Lake by the following morning. They start out with the equipment, as well as a loader to move it, but must contend with slush and water flows that riddle the path. As they traverse a 7-mile ice crossing, Lisa hits a rough patch that causes her to skid briefly. They cross the lake and drive into the night, but a road crew working on an ice bridge will not let them through until repairs are finished.

As part of a government contract, Mark sends Todd to Tadoule Lake with a load of grader blades needed at the local airport. Following a long, poorly maintained road, he eventually finds that the rough conditions have shaken the blades off his trailer. After loading them up by hand, he pours water over them to freeze them in place and starts out again. The load reaches the airport on time, opening the possibility of further government work for Polar. Art heads for the city of Thompson, intending to pick up a load of medical supplies and haul it to Garden Hill. However, he is forced to pull over after his engine develops oil pressure trouble and then cuts out. Finding the oil reservoir to be nearly empty, he calls Mark for a tow into Thompson and passes time in a bowling alley while waiting on repairs. Mark begins to think that Art's problems are due to his driving style.

Although the ice bridge on the road to Deer Lake will not officially reopen until dawn, Darrell and Lisa take a risk by sneaking ahead after the work crew has finished for the night. They both cross safely and deliver their transformers on time. During the return trip, with Lisa bringing back a load of scrap metal, a broken fan belt causes Darrell's engine to overheat and forces him to stop. Lisa draws on her Alaska push trucking experience to keep them both moving and avoid an expensive towing bill. They cover a total of 70 miles in this fashion until reaching a town where Darrell can have repairs done.

Mark informs Todd that the load of grader blades he hauled to Tadoule Lake was short by three when he delivered it, jeopardizing Polar's government contract. Todd is assigned to take a load of lumber and pick up the missing blades in Lynn Lake along the way. That night, with the blades secured, he stops on the roadside to eat dinner over a campfire and sleep in his truck; he reaches Tadoule Lake the next morning and delivers his cargo. Meanwhile, Mike is taking a load of cement to Shamattawa, braving a road roughened by a cold snap. He slides into a snowbank and is unable to free himself by chaining his tires, but a passing trucker pulls him loose so he can finish the run.

As the lake ice starts to give way beneath Art's wheels, he returns to the shore and calls Mark for instructions to find a safer route back to Winnipeg. He reaches the Polar yard safely, to his and Mark's relief. Meanwhile, Alex is taking cement to Pikangikum. Although the road was closed several days earlier, it has been reopened to allow the season's last loads in. After bogging down in the muck on a steep hill, he chains his tires and manages to reach the top so he can complete the run.

Darrell and Lisa have secured a contract to haul two loads to Deer Lake, and Lisa takes building supplies as the first load. However, high temperatures have turned the road into a muddy, slushy mess and left its ice crossing awash in water. In Winnipeg, Darrell learns that Polar has undercut his rates in order to secure the second load of the contract. Offering to reduce his price even farther, he hurries to the Polar yard to hook up the load and get moving, despite Mark's attempt to intercept him.

Darrell improvises a winch, hooking tow straps to an axle and a tree, and pulls himself loose so he can get moving again. He catches up to Lisa the next morning and pulls her free, and the two resume their drive to Winnipeg. After one final, fragile ice crossing, they pull into town to face the likely prospect of extensive repair work due to the deteriorating road conditions.

Art is hauling a double-trailer load of wood fuel pellets to Brochet. Since loads this heavy are not allowed on the final stretch road so late in the season, he recruits Joey Barnes to take half of it. Joey slides into a snowbank on a sharp turn; he manages to free himself, but his maneuvering tears up the road surface and makes the turn more difficult for Art. Both drivers reach Brochet and deliver their loads.

Mark gets a call from a client at a lodge on the Seal River, needing an excavator and a load of building supplies. With no one but Todd immediately available, he offers Darrell and Lisa a chance to split the job with Polar. Lisa volunteers for the run, and she and Todd fly to Churchill, Manitoba to get ready for it. Once there, they must put the loads on sledges and haul them 35 miles across the frozen Hudson Bay to reach their destination. Since trucks are not allowed on the ice, they must use caterpillar track machines instead.

Todd starts first, taking the excavator and a backup driver, but Lisa has trouble getting used to her machine on the rough, jagged ice as she takes the supplies. When Todd gets stuck on a peninsula's snowy hill, the backup driver uses the excavator to push him and the load over the top. As they move away from the shore, they find that the snow layer is so thick that they cannot accurately measure the ice thickness, but they push on regardless. As the sun sets, they encounter large water flows on the ice and Todd finds himself in danger of breaking through.

On the Hudson Bay, Todd and his backup driver work together to pull his load onto sturdier ice. He and Lisa reach the Seal River and deliver their cargo shortly before sunrise. Darrell races over a muddy trail to deliver a load of sheet rock to Pikangikum before the offload site closes at 4:00 that afternoon. Relying on momentum to carry him over the last, steepest hill, he arrives in time and starts back to Winnipeg.

Taking a last-minute load of building supplies to Poplar Hill, Art must contend with a road full of potholes, mud, and slush due to the spring thaw. Remembering his near-breakthrough earlier in the season, he hesitantly ventures onto the season's last open ice crossing. Rough spots and water-filled holes plague him throughout, but he completes the run to close out his season.

While hauling cement and a wood-fired boiler to Kingfisher, Alex encounters an oncoming tanker truck at a slippery corner. As the two drivers swerve to avoid a head-on collision, the tanker sideswipes Alex; neither man is injured, and Alex's truck suffers minor damage. His load still secure, he pushes on and finishes the run late that night.